Musical keyboard



FIG. 1 is a top plan view of a musical keyboard showing my new design;

FIG. 2 is a bottom plan view thereof;

FIG. 3 is a right side view thereof;

FIG. 4 is a left side view thereof;

FIG. 5 is a rear view thereof; and,

FIG. 6 is a front view thereof. 

The ornamental design for a musical keyboard, as shown and described. 